The role of tissue expanders in an anophthalmic animal model.

A study of orbital bony expansion using a custom tissue expander was performed in the anophthalmic cat model. Twelve 6-week-old kittens underwent right unilateral enucleations. Six kittens had immediate insertion of a tissue expander into the orbit. The remaining six served as controls. Every 2 weeks 0.5 cc saline was injected into the expander to a maximum of 5 cc. External horizontal and vertical orbital dimensions were obtained by palpation technique weekly. All animals had preoperative and study conclusion head CT scans with three-dimensional reconstructions performed. Dry skull preparations were done at the study conclusion at 24 weeks. Results demonstrated that tissue expanders were successful in maintaining normal orbital growth and size relative to the contralateral control orbit. The animals with enucleation only had an average difference in vertical and horizontal orbital measurements of -27 and -13 percent when compared with the contralateral normal orbit. In contrast, the enucleation and tissue-expansion animals had vertical and horizontal measurements of +4 and +2 percent (p less than 0.05) when compared with the contralateral orbit. Head CT scans with three-dimensional reconstructions demonstrated normal orbital geometry and volume for the animals with tissue expanders, whereas animals with enucleation only had small hypoplastic orbits. In conclusion, orbital tissue expanders offer a promising new technique in the treatment of anophthalmos.